The basic goal of this research is to further our understanding of the form sensing capabilities of touch as it is used in both everyday tactual exploration and as a passive sensor in sensory aids for the blind and deaf. The research will proceed on two fronts--one, theoretical and the other, experimental. In the theoretial work, I will attempt to develop a computer model that predicts the relative tangibility (tactile legibility) of different sets of patterns, symbols, or characters. In the experimental program of psychophysical research, I plan to investigate a variety of issues concerning the tactual sensing of small two-dimensional patterns. The first of these is to look at the matter of perceptual integration in tactile pattern perception: does it improve with training and how generalizable it is? The second is to attempt to simulate the tactual scanning of two-dimensional patterns using a special scanning arrangement in connection with low-pass spatially filtered vision. The third is to learn more about the mechanoreceptor population mediating the perception of patterns presented with the Optacon vibrotactile display. The fourth is an investigation of tactile localization with an eye to relating this to the physiological substrate. Finally, I am planning anexperiment on visual recognition of high- and log-pass spatially filtered characters to get at an issue pertinent to both vision and touch--is the "overall shape" of a pattern to be distinguished from its lower spatial frequency content.